Abstract [en]

Background In Swedish working life, exposure to cold and exposure to hand-arm vibration (HAV) are two common health hazards. Health effects of HAV in the neurosensory, vascular and musculoskeletal systems are collectively denoted hand-arm vibration syndrome (HAVS), and have been thoroughly studied. Effects of cold exposure in terms of effects on the peripheral neurosensory and vascular system are on the contrary limited, especially in an occupational setting. Effects of cold exposure or cold injury have not previously been assessed with quantitative sensory testing (QST). Commonly reported symptoms after exposure to HAV and after cold injuries, includes cold sensitivity and sensation of cold. Cold sensitivity can also occur without previous exposure to vibration or cold and may have a major impact on quality of life. Other possible risk factors for cold sensitivity need to be assessed. Sensation of cold hands could theoretically imply an early manifestation of damage to the neurosensory or vascular system, and therefore be of importance to enable early detection of vascular and neurosensory HAVS. The purpose of this thesis was to increase the knowledge about health effects from cold and HAV on the peripheral neurosensory and vascular system, with an occupational perspective. The aims were: first, to identify and evaluate health effects and sequelae in the peripheral neurosensory and vascular system due to cold injury and cold exposure; second, to investigate if sensation of cold hands is a predictor for future onset of Raynaud's phenomenon or paresthesia; and third, to identify possible risk factors associated with cold sensitivity.

Methods A case series on 15 military conscripts with local cold injuries in the hands or feet, involving QST and symptom descriptions, was conducted to investigate the hypothesis that cold injuries can result in similar neurosensory and vascular impairments as in HAVS. To assess health effects of cold exposure, a cohort study on 54 military conscripts in cold winter military training, with cold exposure assessments, was conducted. Possible health effects were assessed after 14 months of military training, containing considerable cold exposure, by means of QST, Finger systolic blood pressure after local cooling (FSBP) and a questionnaire. To investigate if sensation of cold hands is a predictor for vascular or neurosensory HAVS we investigated a cohort of 178 employees at a manufacturing company where HAV was a common exposure. The cohort was followed during 21 years and both vibration exposure and health outcomes were assessed regularly. Questionnaire items were used to assess sensations of cold hands as well as signs of Raynaud’s phenomenon and paresthesia. To identify risk factors for cold sensitivity a case-control study was conducted involving 997iiiparticipants from the general population in northern Sweden. The study was cross-sectional and explored possible risk factors for cold sensitivity.

Results Cold injuries and cold exposure were associated with reduced sensibility in QST and increase severity and prevalence of neurosensory and vascular symptoms. Our results did not show any impairment in peripheral blood flow due to cold exposure, detectable by FSBP. The risk of developing Raynaud's phenomenon was increased for workers previously reporting sensation of cold hands (OR 6.3, 95% CI 2.3-17.0). No increased risk for paresthesia in relation to a sensation of cold hands was observed. The identified risk factors for cold sensitivity were frostbite in the hands, rheumatic disease, nerve injury in upper extremities or neck, migraine and vascular disease. When analysing women and men separately, women’s risk factors were frostbite in the hands, rheumatic disease, migraine and cold exposure. Men’s risk factors were frostbite in the hands, vibration exposure and nerve injury in upper extremities or neck. BMI > 25 was a protective factor for both men and women.

Conclusion Cold injury and cold exposure are associated with impairments in the neurosensory system, detectable by QST. Symptoms such as sensation of cold hands and white fingers indicate vascular involvement, even though no vascular impairments due to cold exposure could be detected by objective measurements. A sensation of cold hands is a risk factor for development of Raynaud´s phenomenon, but not for paresthesia. At the individual level, reporting cold hands does not appear to be useful information when considering the possibility of a future development of Raynaud’s phenomenon. Frostbite in the hands is a risk factor for cold sensitivity among both women and men. For women rheumatic disease, migraine and cold exposure are also independent risk factors, and for men, exposure to HAV. Being overweight is a protective factor for both women and men.

Abstract [en]

Background. Local freezing cold injuries are common in the north and sequelae to cold injury can persist many years. Quantitative sensory testing (QST) can be used to assess neurosensory symptoms but has previously not been used on cold injury patients.

Objective. To evaluate neurosensory sequelae after local freezing cold injury by thermal and vibrotactile perception thresholds and by symptom descriptions.

Design. Fifteen patients with a local freezing cold injury in the hands or feet, acquired during military training, were studied with QST by assessment of vibrotactile (VPT), warmth (WPT) and cold (CPT) perception thresholds 4 months post-injury. In addition, a follow-up questionnaire, focusing on neurovascular symptoms, was completed 4 months and 4 years post-injury.

Results. QST demonstrated abnormal findings in one or both affected hands for VPT in 6 patients, for WPT in 4 patients and for CPT in 1 patient. In the feet, QST was abnormal for VPT in one or both affected feet in 8 patients, for WPT in 6 patients and for CPT in 4 patients. Freezing cold injury related symptoms, e. g. pain/discomfort when exposed to cold, cold sensation and white fingers were common at 4 months and persisted 4 years after the initial injury.

Conclusions. Neurosensory sequelae after local freezing cold injury, in terms of abnormal thermal and/or vibration perception thresholds, may last at least 4 months after the initial injury. Symptoms such as pain/discomfort at cold exposure, cold sensations and white fingers may persist at least 4 years after the initial injury.

Abstract [en]

OBJECTIVE: This study aimed to examine the effects of 14 months of military training comprising cold winter conditions on neurosensory and vascular function in the hands and feet.

METHODS: Military conscripts (N=54) were assessed with quantitative sensory testing comprising touch, temperature, and vibration perception thresholds and finger systolic blood pressure (FSBP) after local cooling and a questionnaire on neurosensory and vascular symptoms at both baseline and follow-up. Ambient air temperature was recorded with body worn temperature loggers.

RESULTS: The subjects showed reduced sensitivity to perception of touch, warmth, cold and vibrations in both the hands and feet except from vibrotactile perception in digit two of the right hand (right dig 2). Cold sensations, white fingers, and pain/discomfort when exposed to cold as well as pain increased in both prevalence and severity. There were no statistically significant changes in FSBP after local cooling.

CONCLUSION: Fourteen months of winter military training comprising cold winter conditions reduced sensation from touch, warmth, cold, and vibrotactile stimulus in both hands and feet and increased the severity and prevalence of symptoms and pain. The vascular function in the hands, measured by FSBP after local cooling, was not affected.

Lundström, Ronnie

Pettersson, Hans

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

Nilsson, Tohr

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

Show others...

(English)Manuscript (preprint) (Other academic)

Abstract [en]

Background Raynaud’s phenomenon (white fingers) and neurosensory symptoms are common after hand-arm vibration exposure. Knowledge regarding early signs of a vibration injury are needed.

Aim To investigate the risk of developing Raynaud’s phenomenon and paresthesia in relation to sensation of cold hands in a cohort of male employees at an engineering plant.

Methods We followed a cohort of 241 male manual and office workers at an engineering plant for 21 years. At baseline and each follow-up, sensation of cold, Raynaud's phenomenon and paresthesia in the hands were assessed with questionnaires and vibration exposure was measured. Risk estimates were calculated with Univariate and multiple logistic regression analyses. The analyses were adjusted for vibration exposure and tobacco usage.

Results During the study period, 21 individuals developed Raynaud’s phenomenon and 43 developed paresthesia. When adjusting the risk of developing Raynaud's phenomenon for vibration exposure and tobacco use, the odds ratios were between 6.0 and 6.3 (95% CI 2.2-17.0), depending upon the measure for vibration exposure used in the analysis. No increased risk for paresthesia in relation to a sensation of cold hands was observed.

Conclusions A sensation of cold hands is a risk factor for Raynaud´s phenomenon. At the individual level, reporting a sensation of cold hands does not appear to be useful information to rule in, or rule out, future development of Raynaud’s phenomenon given a weak to moderate predictive value. For paresthesia, the sensation of cold is not a risk factor and there is no predictive value at the individual level.

Stjernbrandt, Albin

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

Carlsson, Daniel

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

Pettersson, Hans

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

Liljelind, Ingrid

Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.

(English)Manuscript (preprint) (Other academic)

Abstract [en]

Aim To identify possible risk factors for cold sensitivity, by comparing cases to controls with regard to demographic and anthropometric characteristics, previous illnesses and injuries as well as ambient exposures.

Methods Through a questionnaire responded to by the general population (n=12,627) cold sensitivity cases (n=502) and matched controls (n=1,004) were identified and asked to respond to a second questionnaire with focus on different aspects of cold sensitivity, hereditary factors, previous diseases, medication, tobacco use as well as exposure to ambient cold climate and hand-arm vibration (HAV).

Results In total, 997 out of 1506 study subjects answered the second questionnaire, 374 cases and 623 match controls. Identified risk factors among the cases were frostbite of the hands Odds Ratio (OR) 10.3 (95% confidence interval (CI) 5.5-19.3), rheumatic disease OR 3.1 (95% CI 1.7-5.7), upper extremity nerve injury OR 2.0 (95% CI 1.3-3.0), and vascular disease OR 1.9 (95% CI 1.2-2.9). Sex differences in risk factors were HAV exposure for men and cold exposure for women increased the risk of cold sensitivity. Rheumatic diseases and migraine increased the risk of cold sensitivity among women but not among men.

Conclusions The present study shows that cold sensitivity is associated with both inherent factors, acquired conditions and external exposures. Among acquired conditions, frostbite, vascular disease, nerve injury, joint disorders and migraine are significantly related to the reporting of cold sensitivity. Among external exposures, both cold climate and HAV exposure are significantly associated to cold sensitivity, and thus suitable targets for primary preventive measures. There was a difference in risk factors related to sex. HAV exposure for men and cold exposure for women increased the risk of cold sensitivity.